INSECTICIDES AXD EQUIPMENT FOR CONTROLLING INSECTS 21 



San Jose scale, pear psylla, thistle aphid on prunes, fruit tree leaf 

 roller, aphids. and spider mites. 



The oil is sometimes used in combination with dinitro compounds 

 to facilitate control of certain pests, in which case less oil is used. 



Dormant oils meeting the above specifications may be purchased 

 from most oil companies and then emulsified. For this purpose bor- 

 deaux mixture, calcium caseinate, blood albumin, soybean flour, casein- 

 ammonia, bentonite, or other emulsifiers may be used. Consult your 

 State agricultural college, or county agricultural agent for directions. 

 Dormant oils are also sold in a self-emulsifiable form ready for dilu- 

 tion with water. 



White oils. — White or summer oils are used in the control of the 

 codling moth, spider mites, and leafhoppers on apples, scale insects, 

 mealybugs, and the red spider and other mites on various ornamental 

 and flowering plants, and the corn earworm on corn. Though some- 

 times used alone, they generally are combined with sprays containing 

 lead arsenate, pyrethrum, derris. cube, or nicotine. 



For most purposes the light oils of approximately 52 seconds vis- 

 cosity (Saybolt, 100° F.) are preferred, but light-medium (about 63 

 seconds viscosity) and medium (about 72 seconds viscosity) are also 

 employed. These oils should have not less than 85 percent of unsul- 

 fonatable residue, and for use on tender plants they are usually diluted 

 so that the final spray contains from y± to 1 percent of oil. On shrubs 

 and evergreens a 2-percent spray may be employed. 



White oil sprays act as adhesives-. and when combined with arseni- 

 cals they interfere with the removal of the poisonous residues. They 

 may also cause injury to foliage and affect the coloration of apples 

 if applied in too large quantities or too frequently. Oil spiny* should 

 not be applied to foliage on which residues from sulfur sprays are 

 present, because severe burning may result. 



Summer oils may be emulsified with the same materials used to 

 emulsify dormant oils, or with nicotine bentonite. They are. how- 

 ever, most commonly sold as miscible or so-called "emulsible" oils con- 

 taining about 97 percent of oil, or paste-type emulsions containing 

 70 to 85 percent of oil. These contain emulsifying agents and need 

 only be diluted with water. The manufacturers usually give full in- 

 structions on the containers for use against various pests. 



The formulas given below have been found effective for use on 

 ornamental plants. 



For red spiders : 



Derris or cube powder (4 percent of rotenone) 1 tablespoonful. 



White oil emulsion (83 percent of oil) 4 teaspoonfols. 



Water 1 gallon. 



For mealybugs and scale insects : 



Nicotine sulfate solution (40 percent of nicotine) IV2 tenspoonfuls. 



White oil emulsion 3 tablespoonfuls. 



Water 1 gallon. 



For newly hatched scale insects on hardy shrubs and also against 

 lacebugs : 



White oil emulsion (83 percent of oil) 1 cupful (or % pint) 



Soap flakes 1 1 _. eupfuls. 



Nicotine sulfate solution 4 teaspoonfols. 



Water 3 1 .* gallons. 



